The new male is keeping the tetras at the top of the water. and the kribs seem to like hanging down low.

Yes, that's exactly right. Staking out his territory: both women and the entire lower part of the tank.

IME, kribs only rise from the bottom for food (if necessary) or to chase other fish.
would ottos be safe in there with the kribs?
I have thought about otos myself, due to an algae problem. I've found a really excellent article about otos, thought it does not adress compatibility issues. You'll find it here:
Otos
Read these for sure. They are helpful, and much shorter.
Kribs with Otos
Kribs in 29 gal
You might want to be careful about getting another krib and having a pair in each tank. It could make it very difficult for you to have other fish in those tanks. Even a small krib seems to fear nothing except a larger, meaner krib. The males are more mellow when there are no females around, but you already have the two females, so I don't know. Be sure you read those last two links. Maybe you can trade a female for a male and have a male in each tank and a female in only one tank. You can let her choose the male, then move the other one.
This is getting long, but I should mention, the reason I have synodontis catfish is that I've read that they are natives of the same general areas of Africa and seem not to be intimidated by the kribs. That is quite true of my eupterus. They do grow to 6 or 7 inches, however, so one can't house too many in a 29 gallon tank. Nigriventris are half that size full grown, but you'd be lucky to ever see them.
Second Opinion
The above link recommends tetras and cories and otos as tankmates for kribs and other cichlids in their group, but I don't know as I'd agree -- not with a breeding pair, anyway. Otherwise, sure.
Anyway, I hope these links help you out.